How to tell my parents?

I would just tell them, but do it in a respectful way. You know what is more annoying that Jesus freaks and preacher? Their polar opposites. Nothing gets accomplished by telling the other person they are wrong or by demeaning them. Just tell them your feelings and tell them you are not happy. Also be prepared for the consequences. If they follow the "its their house and their rules" motto then be prepared to move out and start living on your own.